Fluid-operated pump with double-acting direct-connected booster pump



Feb. 17, 1953 c. J. coBERLY 2,628,563

FLUID-OPERATED PUMP WITH DOUBLE-ACTING DIRECT-CONNECTED BOOSTER PUMPFiled Feb. 2l, 1949 2 SHEETS-SHEET l Patented Feb. 17, 1953FLUID-OPERATED PUMP WITH DOUBLE-- ACTING' DIRECT-CONNECTED BOOSTER PUMPClarence J. Coberly, Pasadena, Calif., assignor, by mesne assignments,to Dresser Equipment Company,V Cleveland, Ohio, a corporation of OhioApplication February 21, `194:9, 4Serial No. 77,588

(CL 10S-5) 9-Claims.

l M-y invention relates to .duid-operated pumps for wells, and, moreparticularly, to a fluid-opy erated pumping device comprising afluid-operated main pump having an auxiliary or booster pump associatedtherewith for increasing the pressure of the Well uid delivered to theinlet of the main pump above that obtaining at the intake of the boosterpump.

Fluid-operated pumps are commonly used in the oil industry for pumpingoil from wells, such a pump comprising, in general, a coupled motor andpump combination set in the well at the level from which oil is to bepumped. In such a combination, the motor comprises a motor piston whichis actuated by alternatively admitting an operating fluid, such as cleancrude oil, under relatively high pressure into opposite ends of amotor-cylinder in which the motor piston is disposed so as toreciprocate the motor piston. The reciprocating motion of the motorpiston is communicated to a pump piston in the pump section of thecombination so that the pump piston pumps ol from the Well.

The fluid being pumped from la Well may contain, in addition to oil,various other fluids such as Water and natural gas, the gas beingpresent in solution or in suspension in the oil in varying quantitiesdepending upon the pressure and temperature conditions prevailing i-nthe well. Also, if the Well is being pumped beyond its capacity toproduce, air may be present in the iluid being pumped. If the oil issaturated or super-saturated With natural gas at the conditions ofpressure and temperature prevailing at the level at which the pump isset, a large portion of the gas may be released during the suctionstroke of the pump piston to form a gas pocket in the pump cylinder.Also, of course, in many Wells the well fluid is merely a froth composedlargely of gas with a relatively small volume of oil. In either case, orif air is drawn into the pump cylinder, a pocket of gas or air in thepump cylinder results, Such pockets result in a material reduction inthe pumping load until such time as the pump piston compresses the gasor air present and strikes solid Well fluid in the cylinder.

Such fluid-operated pumps are frequently set at relatively great depthsand, consequently, a large volumel of operating fluid under relativelyhigh pressure is conned in the supply tubing between the pump in thewell and the apparatus n the surface which delivers the operating iluidto the pump. Due to the appreciable compressibilitz.r of vthis largevolume of operating'iiuid, and due tothe expansion of the supply tubingunder the relatively high pressure at which rvthe'operating fluid ismaintained, a large amount ofenergyis stored under normal operatingconditions. If, because of the presence of gas or air in the pumpcylinder, the load on the pump piston decreases, a sudden increase intherate of 'iiow of operating fluid to the pump occurs, 'therebyaccelerating the motor and pump pistons. IIlhe speed ultimately attainedmay be 'excessive and the pump may race for a portion of a strokeyor fora number of strokes, which is normally detrimental to various componentsof the pump. Various expedients for preventing damage to the pumpmechanism under such conditions have been employed. For example, oWregulators Adisposed in the supply line for vthe operating 'fluid havebeen employed to maintain the rate vof delivery of operating Iluid tothe motor section of the pump below a value which might be harmful tothe pumping equipment. While such rflow governors are practical undermost conditions of operation, they have some disadvantages 'in that theyincrease the cost of the pumping equipment and render the equipmentrather complicated. Also, there is some lag in their operation lsincethey respond only after the condition requiring compensation has alreadydeveloped.

Also, the presence of gas or air in the pump cylinder has a detrimentaleffect on the efllciency of such a duid-operated pump. For example, if,in a given installation, thirty percent of the 4pump cylinder of theduid-operated pump contains free gas or air, the efiiciency of the pump,i. e., the percentage of the volume of the pump cylinder which containssolid Well fluid, Will be only seventy percent. In other Words, undersuch conditions, the duid-operated pump Will pump well iiuid from theWell at only seventy percent of capacity.

In View of the lforegoing considerations, it is a primaryv object of thepresent invention to provide, in combination with a conventionalfluidoperated pump, an auxiliary or booster pump which is adapted todraw Well uidirom the well and toV deliver it to the inlet of thefluid-operated pumpy at lan increased pressure such that the majorportion of the gas or air in the well fluid will not flash out to form apocket in the pump cylinder of the main pump. I accomplishY this byproviding a booster pump which Will maintain the pressure of the Wellfluid passing int-o the pump cylinder of the ma-inxpump` ata 'valueequal to orabove the.pressureprevailingfin the well at the inlet of the.pumpingdevice. A-,further object yof the invention; is to provider a.

3 booster pump which will compress any free gas or air entrained in thewell fluid to a substantial extent before it is delivered to the inletof the main pump.

It will be apparent that employing a booster pump in combination with ahuid-operated main pump in the foregoing manner will obviate, or atleast minimize, the difficulties hereinbefore discussed. In other words,the employment of a booster pump will tend to obviate the racing of themain pump and to increase the pumping eiiiciency thereof. As an example,let it be assumed that the pumping efficiency of the main pump is onlyseventy percent when the pressure at the inlet thereof is approximatelyequal to atmospheric pressure. With the present invention, if theparticular booster pump utilized is adapted to increase the pressure ofthe well fluid delivered to the inlet of the main pump to three hundredpounds per square inch, the free gas or air which otherwise would occupythirty percent of the volume of the pump cylinder of the main pump willbe compressed to occupy only approximately 1.4 percent of the volume ofthe pump cylinder, thereby increasing the efliciency of the main pump toapproximately 98.6 percent under such conditions.

Another object of the present invention is to provide such a pumpingdevice, i. e., such a fluidoperated main pump and booster pumpcombination, in which the booster pump is directly connected to the mainpump so as to be operable thereby. More specifically, it is an object toprovide a duid-operated pumping device wherein the booster pump includesa booster pump piston i directly connected by rod means to one of thepistons of the main pump, preferably the pump piston thereof.

A further object of the invention is to provide in such a pumping devicea booster pump of the double-acting type so as to maintain substantiallyconstant pressure at the inlet of the main pump.

Another object is to provide such a pumping device wherein the main andbooster pumps are removable as a unit.

Still another object is to provide a pumping device of the charactermentioned wherein the main and booster pumps are insertable into atubular receiver which provides a seat.

A further object is to provide a booster pump having pressure reliefvalve means for by-passing fluid discharged by the booster pump pistonto the well in the event that the pressure of the fluid delivered to theinlet of the main pump tends to exceed a predetermined value.

Another object of the invention is to provide a. pumping device whereinthe rod means connecting the various pistons of the main and boosterpumps is hydraulically balanced with respect to operating fluidpressure.

The foregoing objects and advantages of the present invention, togetherwith various other objects and advantages thereof which will becomeapparent, may be attained through the employment of the exemplaryembodiment of the invention which is illustrated in the accompanyingdrawings and which is described in detail hereinafter.

Referring to the drawings:

Fig. 1 is a utility view on a reduced scale showing a fluid-operatedpumping device which embodies the invention as installed in a well;

Fig. 2 is a longitudinal sectional view of the upper-end of a preferredbooster pump of the invention and is taken along the broken line 2-2 ofFig. 1 of the drawings;

Fig. 3 is a downward continuation of Fig. 2 and is taken along thebroken line 3--3 of Fig. l;

Fig. 4 is a downward continuation of Fig. 3 and is taken along thebroken line 4-4 of Fig. 1;

Fig. 5 is a tranverse sectional view taken along the broken line 4-4 ofFig. 2; and,

Figs. 6 and 7 are transverse sectional views respectively taken alongthe broken lines 6-6 and 'I-I of Fig. 4.

Referring particularly to Fig. 1 of the drawings, I show an oil welllined with a casing I0 having perforations II which register with an oilproducing formation through which oil and other fluids may flow into theinterior of the casing, the fluids entering the casing beingcollectively referred to hereinafter as the well fluid. Extendingdownwardly into the casing I0 is a production tubing I3 which is adaptedto convey well fluid to the surface of the ground, and extendingdownwardly into the production tubing in the particular constructionillustrated is a power tubing I4 having a fluid-operated main or primarypump I5 connected to the lower end thereof. Connected to the lower endof the main pump I5 is an auxiliary or booster pump I6 which is adaptedto pump well fluid from the casing I0 to the inlet of the main pump at apressure higher than that obtaining at the intake of the booster pump,as will be discussed in more detail hereinafter. The main and boosterpumps I5 and I6 extend into a tubular receiver I1 which, in effect,forms an extension of the production tubing I3 and which is secured tothe lower end thereof, the main and booster pump assembly seating on atapered seat I8 at the lower end ot the receiver Il, as shown in Fig. 4`of the drawings.

The fluid-operated main pump I5 may 4be of any conventional type, suchas that shown in my Patent No. 2,081,220, issued May 25, 1937, which isadapted to pump well fluid from the casing I0 upwardly through theproduction tubing I3 to the surface. As shown diagrammatically in dottedlines in Fig. l of the drawings, the fluidoperated main pump I5 isprovided with a motor cylinder 2| having a motor piston 22 therein, andis provided with a pump cylinder 23 having a pump piston 24 therein, themotor and pump pistons respectively being provided with longitudinalpassages 25 and 26 therethrough. Connected to the upper end of the motorpiston 22 and communicating with the passage 25 therethrough is an uppertubular rod 21. Connecting the motor and pump pistons 22 and 24 andcommunicating with the respective passages 25 and 26 therethrough is anintermediate tubular rod 29, and connected to the lower end of the pumppiston is a lower tubular rod 30 for directly connecting the main pumpI5 to the booster pump I6 as will be discussed in more detailhereinafter.

Briefly, the fluid-operated main pump I5 operates as follows: operatingfluid, such as clean crude oil, under relatively high press-ure isalternately admitted into opposite ends of the motor cylinder 2| toreciprocate the motor piston 22 therein, such reciprocatory motion ofthe motor piston being communicated to the pump piston 2-4 by theintermediate tubular rod 29. The pump piston 24 discharges fluid intothe production tubing I3, which conveys the uid upwardly to the surface.

Considering the pumping device in more detail, the tubular receiver Il,which, as previously indicated, is connected to the lower end of theproduction tubing I3, includes a plurality of Icomponents, one of thesebeing a tubular coupling 33 which is threaded onto the lower end of theproduction tubing, as bestshovvn in Fig. 2 of the drawings. Threadedvinto the coupling 33 is a sleeve 34 and threaded onto this sleeve is`another tubular coupling 35 havin-g a portion olf reduced diameterwhich is threaded into a tubular -intake iitting 36, as lbest shown inFig. 3 of the drawings. Threaded onto the lower en-dof the intakeiitting 38 is a sleeve 31 and, as best shown in Fig. 4, threaded intothe lower end of this sleeve is another tubular intake fitting 3B.Another sleeve 39 is threaded into the lower end lof the intake fitting38 and threaded ont-o the lower end of the sleeve 39 is a tubular pumpseat member 43 which provides the previously mentioned pump sea-t I8.

Referring to Fig. 2 of the drawings, the main pump I5 terminates at itslower end in a tubular inlet and discharge fitting 43 which is ofsmaller diameter than the internal diameter of the production tubing I3to provide an annular space 44 through which wel-l iiuid discharged lbythe main pump may flow upwardly. The annular space 44 is closed at itslower end when the main and booster pumps I5 and I8 are in theiroperating positions by a sealing ring 45 which is carried in an annulargroove 45 in the fitting 43 and which is adapted for uid-tightengagement with va sleeve 41 pressed into the tubular' coupling 33. Wellfluid discharged by the main pump I5 enters the annular space 44withinthe production tubing I3 through discharge passages 48 in the fitting43, only one of these ydischarge passages being visible in Fig. 2 of thedrawings. The iitting 43 is also 'provided `with longitudinal passageswhich serve las inlet ports 49 for the main plump I5, these inlet portsbeing shown Kbest in Fig. 5 olf the drawings.

Considering the booster pump I6 in more detail, it includes a tubularfitting 52 which is seated against the lower end of the tting 43, thettings 43 and 52 respectively being provided with registering annulargrooves 53 and 54 which communicate with the inlet ports 49 in theiitting 43. The tting 52 is provided with a plurality of longitudinalpassages 55 therethrough, only one of which is visible in Fig. 2 of thedrawings, which also communicate with the registering annular grooves 53and 54.

Seated against'the lower end of the fitting 52 is a tubular iitting 58having a stem 59 which is threaded into the tting 52. Also seatedagainst the lower end of the iitting 52 is another tubular tting 60having an internal diameter which is greater than the external diameterof thewtting 53 tok provide an annular passage 6I therebetween, thepassage 6I communicating with the lower ends of the longitudinalpassages 55 through the tting 52.

Seated against the lower end of the iitting 60 is la tubular dischargeB2 having a plurality of longitudinal passages 63 therethrough whichcommunicate at their upper ends with the annular passage 6I, thepassages 63 being regarded as discharge ports for the booster pump I6 aswill be discussed in more detail hereinafter. A sleeve 64 encloses thefittings' 52 and 80 and is threaded at its ends onto the fittings 43 and62 to clamp the fittings 43, 52, 6G and 62 together.

Referring particularly to Fig. 3 of the drawings, threaded'onto thelower end of the discharge iitting'62 is a booster pump cylinder 61. Theexternal diameter of the booster pump cylinder approachesthe internaldiameters of themtake fittings 36 f andA 38 .so yas to makeysubstantially fluid-tight contact therewith,.but isislightly less thanthe internal diameters of they intake fittings so as tor permitinsertion ofl the'booster pump I6 into and withdrawalth'ereof from thetubular'receiver I1.

Threaded into the lowerV end of the booster pump cylinder 61' isiatubular tting and connected to the' lower end of this fitting byacoupling 69 is. a. member 10 having a tapered external surface 1I whichis adapted to engage the pump seat I8 to support the main and boosterpumps I5 and I6. l

Referring particularly to Figs. Zand 3 ofthe drawings, the lowertubularV rod 30 ofi the'` main pump I5 extends downwardly from thelpumppiston 24 ofthe main pump through the` tubular fittings 43.5258 and 62vinto the booster pump cylinder. 81 wherein it is threaded into a tubularbooster pump piston 15,Y suitable packings 16 and 11 respectively'beingprovided between the rod 30 and the fittings 43,152 andbetween therod:30 and the ttings 82. As best shown in Figs. 3 and 4 of the drawings, atubular rod 18 isthreaded into the lower end of the tubular pumpy piston15 and projects from the lower end of the booster pump cylinder 61through the tubulartting 68 into a balance chamber 19 which is threadedinto theV iitting 68, suitable packing being provided between the rod 18and thefitting 68.

It will be apparent that with thisconstruction, the main and boosterpumps I5 and I6 are hydraulically balanced insofar as the transverse rodareas are concerned, the upper end of the upper tubular rod 21 of theymain pump being exposed to operating iiuid pressure in theipo'wertubing I4, as shown in. Fig. lof the drawings, and the lower end of thetubular rod 18 being exposed to operating iluid Ypressure in thebalanceA chamber 18, as shown in Fig. 4 of the drawings. Operating fluidenters the balance chamber 19 through the upper tubular rod 21, thepassage 25 through` the motor piston 22 of the main pump, theintermediate tubular rod 29, the passage 26 through the pump piston 24of the main pump, the lower tubular rod 30, the tubular booster pumppiston 15 and the tubular rod 18.

Considering the booster pump piston 15 in more detail and referringparticularly to Fig. 3

of the drawings, it includes a tubular core4 83 into which the tubularrods 30 and 18 areV threaded, this core having an external ange 84thereon intermediate its ends. Seated. against opposite sides of theange 84 are oppositely .disposed packing cups 85 whichare formed ofa'exible and resilientmaterial suchas' leather. oil-resistant rubber, orthe like. Extending into and seated against the base wall of eachpacking cup 85 is a spacer 86 and seated againsteachl spacer 85 is apacking cup 81, the packing cups' 81 being oppositely disposed and.being identical Ato the packing cups 85'. Extending intoiand seatedagainst the base walls of the packing cups 81 are spacersv 88,'thelatter being engaged rby` nuts 89 threaded on the ends of the cores 83to Yhold the components of theboos'terpump piston in assembledrelationship.

Referring particularly to Fig. 3 of the :drawings, threaded intothetubulariitting 62 at the upper end of the booster pump'cylinder 61and encircling the rod 30 is a sleeve 92 and threaded onto this sleeveis yan insert 93 which is embedded in an kintake lvalve '94 of the cup'type, the intake valve being formed of ainexibieand resilient nia--terial. Preferably, the valve 94 is formed of a rubber-like material ofan oil-resistant nature, such as neoprena for example. The intake valve94 is provided with a skirt which is adapted to close intake ports 95 inthe booster pump cylinder 61 when the pressure within the booster pumpcylinder exceeds that in the intake ports and which is adapted to bedeformed inwardly to open the intake ports when the pressure in thecylinder 61 is reduced below that in the intake ports. The intake ports95 communicate with an internal annular groove 96 formed in the upperintake fitting 36, the groove 96 in turn communicating with the wellthrough intake ports 91 in the tting 36.

The intake valve 94 is provided with a plurality of longitudinalpassages therethrough which communicate with the discharge ports 63through an annular space |0| between the fitting 62 and the valve 94.Disposed in the annular space IOI and encircling the sleeve 92 is adischarge valve |02 having projections |03 which are insertable into thepassages |00 in the intake valve 94 to close them, the discharge valvebeing biased toward its closed position by a spring |04 which is seatedagainst the lower end of the discharge tting 62. The spring |04 isadapted to permit the discharge valve |02 to open when the pressure inthe booster pump cylinder 61 above the booster pump piston 15 exceedsthe pressure in the discharge ports 63, and to close the discharge valvewhen such pressure is less than that in the discharge ports.

Referring now to Fig. 4 of the drawings, threaded into the tubular tting68 at the lower end of the booster pump cylinder 61 is a sleeve |01 ontowhich is threaded an insert |08 embedded in an intake valve |00 which isidentical to the intake valve 94, the intake Valve |09 controlling flowthrough intake ports I|0 in the booster pump cylinder. The intake ports||0 communicate with an internal annular groove |I| in the lower intaketting 30, which groove in turn comunicates with the well through intakeports I |2 in the tting 38.

The intake valve |09 is provided with longitudinal passages |I5therethrough which correspond to the longitudinal passages |00 throughthe intake valve 94 and which communicate with an annular space |I6between the tting 68 and the intake valve |09. Disposed in the annularspace |I6 and encircling the sleeve |01 is a discharge valve ||1 havingprojections IIB which are insertable into the longitudinal passages I|5to close them, the discharge valve I1 being identical to the dischargevalve |02 and being biased toward its closed position by a spring II9which is seated against the fitting 68.

Referring to Figs. 4 and 7 of the drawings, communicating with theannular space |I6 containing the discharge valve ||1 is a plurality ofradial ports |22 in the booster pump cylinder 61, these portscommunicating with an annular groove |23 in the lower intake itting 30.Formed in the tting 38 and communicating at their lower ends with theannular groove |23 are longitudinal passages |24 which, as best shown inFigs. 3 and 4 of the drawings, communicate at their upper ends with anannular passage |25 between the sleeve 31 of the tubular receiver I1 andthe booster pump cylinder 61. rIhe annular passage |25 communicates atits upper end with the lower ends of longitudinal passages |26 in theupper intake fitting 36, the passages |26 communicating at their upperends with an annular 8 groove |21 in the fitting 36. The groove |21communicates with the annular space |0I containing the discharge valve|02 through radial ports |28 in the booster pump cylinder 61.

Considering the operation of the booster pump I6, during the upwardstroke of the motor and pump pistons 22 and 24 of the main pump I5, thebooster pump piston 15 is moved upwardly in its cylinder 61 by the rod30, the booster pump piston being shown in its uppermost position inFig. 3 of the drawings. During its upward stroke, the booster pumppiston 15 discharges well fluid contained in the cylinder 61 thereaboveinto the annular space |0I containing the discharge valve |02, thedischarge valve unseating to permit this to occur. Outow into the wellthrough the intake ports is prevented by the skirt of the cup-typeintake valve 94. From the annular space I0 I, the well duid dischargedby the booster pump piston 15 enters the discharge ports 63 andultimately reaches the inlet ports 49 of the main pump I5 through thepreviously-described intervening passages.

Also during the upward stroke of the booster pump piston 15, well fluidis drawn into the booster pump cylinder 61 beneath the piston throughthe intake ports I I2, the annular groove I I I and the intake ports II0, the skirt of the cuptype intake valve |09 deforming inwardly topermit this to occur. At the same time. the discharge valve I I 1 closesthe longitudinal passages H5 through the intake valve |09.

During the downward stroke of the motor and pump pistons 22 and 24 ofthe main pump I5, the rod 30 moves the booster pump piston 15 downwardlyin its cylinder 61. During its downward stroke, the booster pump piston15 discharges well fluid contained in the cylinder 61 therebeneaththrough the longitudinal passages H5 in the intake valve |09 and intothe annular space ||6 containing the discharge valve II1, the dischargevalve ||1 opening to permit this to occur. During the downward stroke ofthe booster pump piston 15, the intake valve |09 closes the intake portsI I0 to prevent outiiow into the well. From the annular space II6, thewell fluid discharged during the downward stroke of the booster pumppiston flows upwardly to the discharge ports 63 by way of the radialports |22 in the booster pump cylinder 61, the annular groove |23 in theintake fitting 38, the longitudinal passages |24 in this fitting, theannular passage |25 between the sleeve 31 and the booster pump cylinder,the longitudinal passages |26 in the intake fitting 36, the annulargroove |21 in this fitting and the radial ports |20 in the booster pumpcylinder. From the discharge ports 63 the uid discharged during thedownward stroke of the booster pump piston 15 ows upwardly through thepreviously-described intervening passages to the inlet ports 49 of themain pump I5.

Thus, by discharging well uid on both strokes of the booster pump piston15, the booster pump I6 delivers well uid to the inlet ports 49 of themain pump I5 at a substantially constant rate and at a substantiallyconstant pressure, which is an important feature of the invention.

Referring particularly to Fig. 4 of the drawings, the booster pump I6includes pressure relief valve means |35 for by-passing duid dischargedby the booster pump piston 15 into the well in the event that thepressure of the well fluid delivered to the inlet ports 49 of the mainpump I5 exceeds a predetermined value. The pressure relief valve means|35 is ycarried by `the member 'I0 which is seated on the pump seat I8and includes a ball valve |36 carried by a retainer |31 and urged intoengagement with a seat |38 by a spring |39'.v The seat |38 encircles apassage |40 which communicates with a vrecess |4I in the member "Id, thefitting 6B being provided with longitudinal passages |42 which connectthe recess |4I to the annular space I i6 containing the discharge valveIII. The member I is also provided with radial passages |43 whichconnect the recess I4i toan annular passage |44 between the booster pumpI6 and the tubular receiver I'I, the annular passage |44 communicatingat its upper end with the annular groove |23 in the fitting 38. Thus,well duid discharged by the booster pump piston 'I5 may flow into thepassage |40 controlled by the ball valve |36 through the longitudinalpassages |42 in the fitting 68, or through the .annular passage |44.

In the event that the pressure .of the well fluid discharged by thebooster pump piston l rises above a predetermined value for any reason,the spring |38 is compressed toA permit the 'ball valve |36 to unseat,thereby permitting fluid to flow through the passage |40 into a recess|45 containing the ball valve |36, the retainer |31 and the spring |39.The member is providedwith radial passages |46 through which uid mayflow from the recess |45 into the well upon unseating of the ball valve|36. I

Thus, the auxiliary or booster pump I6 delivers well duid to the inletports 49 of the fluid-operated main pump I5 at an elevated pressure tominimize the formation of gas or air pockets in the pump cylinder 23 ofthe main pump, whereby to increase the eiciency of the main pump and tominimize'the possibility of damage to the components thereof which mayresult from the formation of gas or air pockets in the pump cylinder 23as Apreviously discussed. The booster pump I6 preferably delivers arelatively large volume .of well fluid to the main pump at a relativelylow pressure, the effective cross sectional area .of ythe booster pumppiston 'I5 being substantially larger than that of the motor piston 22of the main pump to accomplish this. In practice, the ratio of boosterpump piston area to motor piston area may be four to one, for example.Thus, the major portion of the work necessary to pump well fluid to thesurface is performed by the main pump I5, the function of the boosterpump I6 being to deliver the well uid to the main pump at a pressuresufficient only to prevent excessive formation of gas pockets in thepump cylinder 23 of the main pump, which pressure preferably exceeds thepressure obtaining at the intake ports 95, 9i and IIB, |I2 of thebooster pump.

In the event that the pressure developed by the booster pump I6 risesabove the value determined by the spring |39 of the pressure reliefvalve means |35 for any reasons, the ball valve |36 will unseat toby-pass fluid to the well, as hereinbefore discussed.

As will be apparent, the main pump I5 and the booster pump I6 may beinstalled in or removed from the well as a unit, the booster pump beingslidably positioned in the tubular receiver II. As hereinbeforediscussed, when the main and booster pumps are in their respectiveoperating positions with the booster pump in engagement with the pumpseat I8, the sealing ring 45 carried by the main pump provides afluid-tight seal between the main and booster pumps.

Although I have disclosed an exemplary embodiment of the inventionv forpurposes ,Ofjillus tration, it will be understood that various changes,modifications and substitutions maybe incorporated in the specificembodiment' 4dis"- closed without necessarily departing 'from the spiritof the invention and I hereby" reserve .the right to all such changes,modifications and substitutions.

I claim as my invention:

1. In a fluid-operated pumping device, the combination of: ,afluid-operatedmain pump"Y of. the reciprocating type a'clap'tedto beppsi'tidnd in a well and to pump well fluid fromtie' ,Well to thesurface, said main. pump being" provided with an inlet port.; adouble-acting auxiliary pump of the reciprocating vtype' provided'lWithintake port means which is vadapted'to come municate with the well andprovided, with rdisgcharge port means; means providing a LIgised,Vcommunieatinjg pressure-maintaining` passage only with said inlet portand 'saiddiseharge' `port means so as to maintain rfluid'pressure insaid inlet port substantially .equal to that in saiddischarge portmeans; .and means mechanically connecting said auxiliary pumpk to saidmain pump lfor operating said auxiliary pump so as to pump well fluidfrom the well to said'inlet port at a `pressure higher than .that insaid'jintafke' port means.

2. In a fluid-operated pumping device, the combination of:auid-operatedpmain Dump' of the reciprocating type adapted'toDepositioned ina well and to pump well fluid from thewell to thesurface, said .main pump` including .Qonnected motor and pump. pistonsand "being provided with 1an inlet port.; a .doublelactingfauxiliarypump of ,the reciprocating type axially aligned with `the. main pump.and inc'ludirjig''yav pump piston, said auxiliaryspum'p being providedwith intake port means,y adaptedjto lconimunicate with the well .anddischarge port.

means; means providing a. closed, pressureport substantially .equallto.that in. said ,discharge port means; and rod means'directly/connecting' said pump piston of said auxiliary pump to one ofsaid pistons of said main pump for operating said auxiliary pump so asto pump Well fluid from the well into said inlet port at a pressurehigher than that in said intake port means.

3. In a fluid-operated pumping device, the combination of: afluid-operated main pump of the reciprocating type adapted to bepositioned in a well to pump well fluid from the well to the surface,said main pump including connected motor and pump pistons and beingprovided with an inlet port; a double-acting auxiliary pump of thereciprocating type axially aligned with said main pump and provided witha pump cylinder having a pump piston reciprocable therein, saidauxiliary pump being provided with intake port means adapted tocommunicate with the well and communicating with the ends of saidauxiliary pump cylinder, and being provided with discharge port meanscommunicating with the ends of said auxiliary pump cylinder, saidauxiliary pump having intake valve means controlling flow of fluidthrough said intake port means, and having discharge valve meanscontrolling flow through said discharge port means; means providing aclosed, pressure-maintaining passage communicating only with said inletport and said discharge port means so as to maintain uid pressure insaid inlet port substantially equal to that in said discharge portmeans; and rod. means directly connecting said auxiliary pump piston toone of said pistons of said main pump for operating said auxiliary pumpso as to pump well fluid from the well into said inlet port at apressure higher than that in said intake port means.

4. A fluid-operated pumping device as set forth in claim 2 wherein saidauxiliary pump includes a balance chamber and wherein said rod means istubular and extends into said balance chamber.

5. In a duid-operated pumping device, the combination of: ailuid-operated main pump of the reciprocating type adapted to bepositioned in a well to pump well fluid from the well to the surface,said main pump including connected motor and pump pistons and beingprovided with an inlet port; a double-acting auxiliary pump of thereciprocating type axially aligned with said main pump, said auxiliarypump including a pump cylinder having a pump piston reciprocabletherein, said auxiliary pump being provided with intake port meansadapted to communicate with the well and discharge port means; meansproviding a closed, pressure-maintaining passage communicating only withsaid inlet port and said discharge port means so as to maintain fluidpressure in said inlet port substantially equal to that in saiddischarge port means; rod means directly connecting said auxiliary pumppiston to one of said pistons of said main pump for operating saidauxiliary pump so as to pump Well iiuid from the well into said inletport at a pressure higher than that in said intake port means; andpressure relief valve means carried by said auxiliary pump cylinder forby-passing fluid from said discharge port means to the well.

6. In combination with production and power tubings set in a well and atubular receiver which is connected to one of said tubings and which isprovided with a seat, a fluid-operated pumping device adapted to beinserted into said receiver and to seat on said seat, comprising: afluid-operated main pump of the reciprocating type provided withconnected motor and pump pistons and an inlet port; a double-actingauxiliary pump axially aligned with said main pump, said auxiliary pumpincluding a pump cylinder having a pump piston reciprocable therein, andsaid auxiliary pump being provided with intake port means adapted tocommunicate with the Well and discharge port means; means providing aclosed. pressure-maintaining passage communicating only with said inletport and said discharge port means so as to maintain fluid pressure insaid inlet port substantially equal to that in said discharge portmeans; and rod means directly connecting said auxiliary pump piston toone of said pistons of said main pump for operating said auxiliary pumpso as to pump well fluid from the well into said inlet port at apressure higher than that in said intake port.

7. A huid-operated pumping device as defined in claim 2 wherein saidauxiliary pump is secured to said main pump so that said main andauxiliary pumps are installable in and removable from the well as aunit.

8. A Huid-operated pumping device as defined in claim 6 wherein saidauxiliary pump is secured to said main pump so that said main andauxiliary pumps are insertable into and removable from said receiver asa unit.

9. A fluid-operated pumping device as defined in claim 6 includingannular sealing means carried by said pumping device intermediate saidmain and auxiliary pumps and adapted to engage said receiver influid-tight relation therewith.

CLARENCE J. COBERLY.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,022,781 Pigott Dec. 3, 19352,081,223 Coberly May 25, 1937 2,134,465 Lacy Oct. 25, 1938 2,255,305Zehner Sept. 9, 1941 2,284,505 Zehner May 26, 1942 2,314,583 KitsmanMar. 23, 1943

